MODULE OF INSTRUCTION
Oracle Database Welcome to the 1st module of this course Database Management System 1! For this lesson, we will introduce to you the type of database system and its components.
Database Management
A database-management system (DBMS) is a collection of
System
interrelated data and a set of different application programs use to access those data. This is a collection of related data with an implicit meaning and hence is a database.
After completing this lesson, the student should be able to:
Understand what is the difference between data, information, database and database management system.
Discuss the advantage and disadvantage of database management system.
Familiarize
with
the
term
ER-Model,
Entities,
Relationship and Attribute.
The collection of data, also known as the database, contains information relevant to an enterprise and or in organization. The main goal of a Database Management System or also known as DBMS is to provide a way to store, manage and retrieve database information that is both convenient and efficient. By data, we mean known facts that can be recorded and that have implicit meaning. For example, consider the
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student record which have the complete names, course, year level, and subjects enrolled. With You may have recorded this data belongs to the student. A datum – a unit of data – is a symbol or a set of symbols which is used to represent something. The relationship between symbols and what they represent is the true value of what it mean by information. Hence, information is interpreted data – data supplied with semantics. Knowledge refers to the practical use of information. While information can be transported, stored or shared without many difficulties the same cannot be said about knowledge. Knowledge necessarily involves a personal experience.
Database systems are
designed
to
manage
bulk
of
information. The process of managing the data involves both defining structures for storage of information and providing mechanisms for the manipulation of information. In addition, the database system must ensure the security of the information stored, in the event of system crashes or attempts at unauthorized access. If the data are shared to different users, the system must avoid possible anomalous results. Because information is so important in most organizations, the reason why computer scientists have developed a large body of concepts and techniques for managing data in Database system which is known as Database Management System.
Types of Handling Data
Handling of data is divided into three types: 1. Data Processing this is the term generally used to ___________________ ___________________________ ________________ _________________ __________________ __________________ _________________ __________________ _______________ _____ 2
MODULE OF INSTRUCTION describe what was done by the large computers in the late 1940's until 1980's. The process of data processing before is still being done by most large organization.
Example
large
volumes
of
raw
transaction data fed into programs that update a master file, with fixed format reports written to paper. 2. The term Data Management Systems refers to an expansion of data processing where the raw data that fed into programs that update a master file, with fixed format reports written to paper. is now fed into the system from a variety of sources, including but not limited to ATMs, EFT, and direct customer entry through the Internet. The master file concept has been largely displaced by database management systems, and static reporting replaced or augmented by ad-hoc reporting and direct inquiry, including downloading of data by customers.
3. File Oriented Approach – The computer system in the earliest business were used to process and manage business records and produced information. This is faster and more accurate compared to manual system. these systems stored groups of records in separate file, and now called as file processing. In a common file processing systems, each department has its own files, designed and stored specifically for those applications.
Characteristics of Database
1. Concurrent Access – is is one of the characteristic of a database system that allows several users to access the
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database
concurrently
and
simultaneously.
And
example of this is answering different questions from different users with the same database is a central aspect of an information system. The concurrent use and access of data increases the economy of a system. 2. Structured and Described Data – once of the fundamental feature of the database approach is that the database system does not only contain the data but also the complete definition, structure and description of these data. These descriptions are the complete details about the extent, the structure, the type and the format of all data and, additionally, the relationship between the data. This kind of stored data is called metadata. 3. Separation of Data and Applications – As the structure and describe data is described through metadata which is also stored in the database. Application software does not need any knowledge about the physical data storage like encoding, format, storage place, structure and the like. The primary task of application software is to communicate with the management system via a standardized interface with the help of a standardized language like SQL or also know Structure Query Language. The access to the data and the metadata is done by the DBMS. In this way, all the applications can be totally separated from the data. 4. Data Integrity - Data integrity is a mean of quality and the reliability of the data of a database system. In a broader sense data, integrity includes also the ___________________ ___________________________ ________________ _________________ __________________ __________________ _________________ __________________ _______________ _____ 4
MODULE OF INSTRUCTION protection of the database from unauthorized access and changes. 5. Transactions - A transaction is a group of actions which are done within a database to bring it from one consistent state to a new consistent state. A transaction is atomic which means that it cannot be divided up any further. Within a transaction, all or none of the actions need to be carried out. 6. Data Persistence - Data persistence means that in a database management system all data is maintained as long as it is not deleted explicitly in the database. The life span of data needs to be determined directly or indirectly be the user and must not be dependent on system features which means a database administrator may identify data that must be deleted or retained.
Advantages and Disadvantages of a DBMS
ADBMS has many advantages 1. Data independence: an application programs should be as independent as possible from details and structure of data representation and storage. The Database Management System can provide an abstract view of the data to insulate application code from such details. 2. Efficient data access: A Database Management System utilizes a variety of sophisticated techniques to store and retrieve data efficiently. This feature is especially important if the data is stored on external storage devices. 3. Data integrity and security: If data is always accessed through the Database Management System,
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the DBMS can enforce integrity constraints on the data. DBMS can enforce access controls that govern what data is visible to different classes of users. 4. Data administration: When several users share the data simultaneously, centralizing the administration of data can offer significant improvements and security. 5. Concurrent access and crash recovery: A Database Management System schedule concurrent accesses to the data in such a manner that users can think of the data as being accessed by only one user at a time. Furthermore, the DBMS protects users from the effects of system failures. 6. Reduced
application
Database
Management
development
System
time: The
supports
many
important functions that are common to many applications which accesses data stored in the DBMS. This is connected to the high-level interface of data that facilitates quick development of applications. This applications are likely to be more robust than applications developed from scratch or manualy because many important tasks are handled by the DBMS
instead
of
being
implemented
by
the
application.
Disadvantages of a DBMS 1. Danger of a Overkill: For small and simple
applications or for single users a database system is often not advisable. 2. Complexity:
Having
database
system
creates
additional complexity and requirements into the ___________________ ___________________________ ________________ _________________ __________________ __________________ _________________ __________________ _______________ _____ 6
MODULE OF INSTRUCTION company and or organization. Managing the operation of a database management system with several users and databases is quite costly and demanding. 3. Qualified Personnel: The professional operation of a
database system requires fully trained staff. Without a qualified database administrator nothing will work for long as no one will able to maintain and manage the data store in the database. 4. Costs: having a database management system means new costs are generated for the system itself but also for additional hardware and the more complex handling of the system. 5. Lower Efficiency: A database system is a multi-use software or also known as generic software which is often less efficient than specialized software which is produced and optimized exactly for one problem.
Instances, Physical and Logical Schemas
As values are inserted and deleted information in the database also changes. The group of information stored in the database at a particular moment is called an instance of the database. While the overall design of the database is called the database schema. Schemas are changed infrequently, if at
all.
The physical schema of database describes the design of the database at the physical level, while the logical schema describes the design of the database at the logical level. Database also have several schemas schemas at the the view level, also known as subschemas that describe different views of the database. The Application programs are used to exhibit
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physical data independence given that it to do not depend on the physical schema, and thus need not be rewritten if the physical schema changes.
Data Models
The underlying the structure of a database da tabase is the data model: it is a collection of conceptual tools for describing data, relationships, semantics, and integrity constraints.
The Entity-Relationship Model
The entity-relationship (E-R) data model is a collection of different objects, called entities, and of relationships among these objects. While an entity is a something that describes an object from other objects.
The connection or association among several entities is called a r elationship. elationship. The logical structure or schema of a database can be represented graphically by an E-R diagram.
Relational Model
The relational model uses a collection of tables to represent both data and the relationships among those data a table in relational model is also know an Entity. Each table or entity has multiple columns or also known as an attribute which is used to uniquely identify once table or entity to the other, and each column has a unique name. The data is arranged in a relation which is visually represented in a two dimensional table meaning it is a relationship or connections of two or more table. In the database, the data is inserted into the table in the form of tuples or also known as values per row. The ___________________ ___________________________ ________________ _________________ __________________ __________________ _________________ __________________ _______________ _____ 8
MODULE OF INSTRUCTION relational model is implemented in database where a relation is represented by a table, a tuple is represented by a row, an attribute is represented by a column of the table, attribute name is the name of the column such as ‘identifier’, ‘name’, ‘city’ etc., and attribute value contains the value for column in the row.
Constraints during or after the creation of table a user may apply the constraint to the table and form the logical schema. A constraint is used to uniquely identify a data and restrict access to the database. In order to identify properly the selection of which particular row/tuple row/tuple from from the table, the attributes i.e. column names are used (ID, LASTNAME, COURSE), and to expedite the selection of the rows some fields are defined uniquely to use them as indexes, this helps in searching the required data as fast as possible.
Lesson Summary:
In this lesson, you should have learned the following.
Database
Database Management System
ER Model
Advantage and Disadvantage if database
Terms to Remember!
Application programs - are said to exhibit physical
data independence if they do not depend on the physical schema.
Data-known facts that can be recorded and that have
implicit meaning.
Database Management System 1
Data integrity- is a byword for the quality and the
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reliability of the data of a database system.
Database-management system (DBMS) - is a
collection of interrelated data and a set of programs that is used to access and manipulate data stored in the database.
Database schema - the overall design of the database
is called the
Database systems - are designed to manage large
bodies of information.
Datum – a unit of data – is a symbol or a set of
symbols
which
is
used
to
represent
relevant
information in the database.
data – data data Information - is also known as interpreted data – supplied with semantics.
Instance of the database – is the collection of
information stored in the database at a particular moment which means the current state of the data.
Logical schema - describes the design of the database
at the logical level.
Physical schema - describes the design of the
database at the physical level,
Relationship - is an association or connection of one
entity to other entities.
Transaction - is a group of actions or changes made
to the database to bring it from one consistent state to a new consistent state.
Textbook: ___________________ ___________________________ ________________ _________________ __________________ __________________ _________________ __________________ _______________ _____ 10
MODULE OF INSTRUCTION •
Oracle Press (2010). Applied Oracle Security
References:
References
•
Pratt, Philip J. (2010). Database management systems
•
Rob, Peter & Coronel, Carlo (2009). Database Management Systems
•
Schwalbe, Kathy (2011). Management of o f Information Technology Projects
•
Wheeler, Evan (2011). Security Risk Management : Building an Information Security Risk Management Program from the Ground Up
Supplementary Links for Reading and Videos
Supplementary Reading http://www.eazynotes.com/pages/database-managementsystem/introduction-to-dbms.html https://www.w3schools.in/dbms/intro/ http://www.cs.ubc.ca/nest/dbsl/intro.html Supplementary Video https://www.youtube.com/watch?v=1057YmExS-I https://www.youtube.com/watch?v=kTVLO9F1QoY https://www.youtube.com/watch?v=0uWA4zps-3k Suggested Reading
•
SQL Tutorial. In ws3schools, Retrieved from http://www.w3schools.com/sql/default.asp
•
Database management system. In Encyclopedia Britannica, Retrieved from http://www.britannica.com/EBchecked/topic/152201/d atabase-management-system-DBMS.
•
SQL. In Encyclopedia Britannica, Retrieved from http://www.britannica.com/EBchecked/topic/569684/ SQL
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•
Database Administration. In Encyclopedia.com, Retrieved from http://www.encyclopedia.com/topic/Database_adminis tration.aspx
•
SQL. In Encyclopedia.com, Retrieved from http://www.encyclopedia.com/topic/SQL.aspx
•
Tutorialspoint.com
•
oracle.com
•
apex.oracle.com
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